Do size 7 diapers exist??

My daughter is 16 months old and has been wearing size 6 diapers, well the size 6 diapers are getting to be too small for her. I don't really want to buy a big box of 6's If she isn't going to be wearing them for much longer...

Here's my issue!!

I cannot find size 7 diapers ANYWHERE!

I've been to several different Wal-Mart's, Target, Winco, Costco... and nothing. It's not like they're all out of them either, there's just not a place for them. I feel like my oldest daughter wore size 7 and even size 8. I just can't find anything bigger than size 6. At this point I don't even care about brand, or how big the box is, I just need some 7's.

What should I Do!?!?